ELECTROMECHANICAL CHARACTERIZATION OF PIEZOELECTRIC ACTUATORS SUBJECTED TO A VARIABLE PRELOADING FORCE AT CRYOGENIC TEMPERATURE

Piezoelectric actuators are actually used in Fast Active Cold Tuning Systems (FACTS) for SRF cavities. The characteristics, performances and lifetime of these actuators depend on the preloading force applied by the cavity and the FACTS to the piezostacks. Experimental data are needed for reliable and optimum operation of piezostacks in superconducting protons or electrons linacs. In the frame of the CARE project supported by EU, we designed and constructed a dedicated apparatus for studying the electromechanical behaviour of prototype piezoelectric actuators subjected to variable preloading force at cryogenic temperatures. This device was successfully used for testing piezoelectric actuators prototypes for T in the range 2K-300K. The dielectric properties as well as dynamic properties were measured including the actuator characteristics when used as force sensor. The corresponding data are reported and discussed